Research On Low-Complexity Dectection Algorithms For Spatial Modulation

Spatial Modulation(SM) is a new modulation scheme for multi-antenna wireless communications. Only one antenna is switched on for transmission while others keep idle. The source bits are conveyed not only by constellation symbol, but also antenna index. Thus only one RF chain is needed at the transmitter without the Inter-Antenna Synchronization.The low complexity detector is needed at the receiver. Recently, SM attracts more and more concerns for low hardware cost and high energy efficiency.Sphere Decoding(SD) decoders can reduce the complexity of Maximum Likelihood(ML)while keep the close optimal bit-error-ratio(BER) performance. There are two well-known SDs: Receiver-centric SD(SM-Rx) and Transmit-centric SD(SM-Tx). The SM-Rx offers high complexity with few number of receiver antennas while SM-Tx is not suitable for large number of transmitter antennas. Therefore, an improved Transmit-centric SD algorithm without triangular decomposition is proposed in this paper, GSM-Tx. Simulation results show that the proposed GSM-Tx can reduce complexity dramatically while maintaining the optimum BER performance, especially with large number of transmit antennas and high order modulation, without restrictions of SM-Rx and SM-Tx.Generalised Spatial Modulation(GSM) is a relatively new scheme to further increase the spectral efficiency of Spatial Modulation(SM). GSM allows several transmit antennas to be active at a time to simultaneously transmit a data symbol. As a result, Ntrequired to achieve a certain spectral efficiency is reduced by more than a half in GSM as compared to SM. However, there are hardly research which focuses on low complexity decoders for GSM, especially for high spectral efficiency GSM. In this paper, we show that the SM-Rx and proposed GSM-Tx are applicable to GSM. Simulation results show that the proposed GSM-Tx offers lower complexity, especially for high spectral efficiency GSM/SM.In order to further exploit the signal space more efficiently and increase spectral efficiency and BER performance of GSM, a novel modulation method termed as multiple antenna state spatial modulation(MAS-SM) is proposed in this paper. In MAS-SM scheme, the elements of the antenna vector is no longer two-state as in the traditional GSM scheme, but is rotated by integral multiple of an angle ?, which makes the signal vectors of MAS-SM spaced uniformly in the signal space. In MAS-SM scheme, more antenna combinations can be used and the minimum Euclidean distance is increased. Finally, simulation results show that MAS-SM scheme has a better BER performance than GSM for the same spectral efficiency.